Subclinical Hypothyroidism in Childhood — Current Knowledge and Open Issues

Subclinical hypothyroidism is defined as serum levels of TSH above the upper limit of the reference range, in the presence of normal concentrations of total T4 or free T4. This biochemical profile might be an indication of mild hypothyroidism, with a potential increased risk of metabolic abnormalities and cardiovascular disease recorded among adults. Whether subclinical hypothyroidism results in adverse health outcomes among children is a matter of debate and so management of this condition remains challenging. Mild forms of untreated subclinical hypothyroidism do not seem to be associated with impairments in growth, bone health or neurocognitive outcome. However, ongoing scientific investigations have highlighted the presence of subtle proatherogenic abnormalities among children with modest elevations in their TSH levels. Although current findings are insufficient to recommend levothyroxine treatment for all children with mild asymptomatic forms of subclinical hypothyroidism, they highlight the potential need for assessment of cardiovascular risk among children with this condition. Increased understanding of the early metabolic risk factors associated with subclinical hypothyroidism in childhood will help to improve the management of affected individuals.

Key points

• Subclinical hypothyroidism among children is often a benign and remitting condition, for which risk of progression to overt hypothyroidism depends on the underlying cause (for example, autoimmune disease)
• The optimum management of children with subclinical hypothyroidism depends on the aetiology and degree of TSH elevation and should be individually tailored
• The benefits of levothyroxine therapy are clear for the severe forms of subclinical hypothyroidism; however, uncertainty about this approach still exists for the mild forms of the condition
• In the absence of therapeutic intervention, clinical evaluation and thyroid function tests should be regularly performed to ensure early identification of children who might benefit from treatment
• Growth and neurocognitive outcomes do not seem to be affected in mild subclinical hypothyroidism; however, subtle proatherogenic abnormalities have been detected among children with modest elevations of TSH concentration
• Cardiovascular risk assessment among children and adolescents with subclinical hypothyroidism could help to prevent cardiovascular disease in adulthood

Read more: Subclinical Hypothyroidism in Childhood — Current Knowledge and Open Issues

Source: NatureReviewsEndocrinology